The present invention relates to the manufacture of portable electronic devices, including at least one integrated circuit chip embedded in a support and electrically connected to interface elements consisting of a connection terminal block.
These portable electronic devices constitute for example contact smart cards.
Smart cards are intended for performing various operations such as, for example, banking or telephone communication operations, various identification operations, or operations of the cash dispensing type.
Contact cards have metallisations flush with the surface of the card, disposed at a precise point on the card body, defined by the usual standard ISO 7816. These metallisations are intended to come into contact with the reading head of a reader with a view to electrical transmission of data.
As currently produced, smart cards are thin portable elements with standard dimensions. ISO 7810 corresponds to a card with a standard format 85 mm long, 54 mm wide and 0.76 mm thick.
The majority of smart card manufacturing processes are based on the assembly of the integrated circuit chip in a subassembly known as a micromodule which is inset, that is to say placed in a cavity provided in a card body, using techniques known to experts.
A conventional method is illustrated in FIG. 1. Such a method consists in gluing an integrated circuit chip 10 by disposing its active face with its contact pads 11 upwards, and gluing its opposite face to a dielectric support sheet 15. The dielectric sheet 15 is itself disposed on a contact grid 18 such as a nickel- and gold-plated copper metallic plate for example. Connection wells 16 are formed in the dielectric sheet 15 in order to enable connection wires 17 to connect the contact pads 11 of the chip 10 to the connection areas on the grid 18.
According to certain variants, it is possible to glue the chip 10, with its active face upwards, directly on the contact grid 18, and then to connect it by hard wiring 17.
In such a variant, the grid 18 is deposited on a dielectric support 15 and the contact and connection areas on the said grid are defined by chemical etching or any other known means.
A protection or encapsulation step then protects the chip 10 and the soldered connection wires 17. Use is generally made of a technique known as xe2x80x9cglob topxe2x80x9d in English terminology, which designates the coating of the chip from above. This technique consists in pouring a drop of resin 20, based on epoxy for example, thermosetting or cross-linking under ultraviolet, onto the chip 10 and its connection wires 17.
The dielectric support 15 with the chip 10 glued and protected by the resin 20, is cut in order to constitute a micromodule 100, which is inset in the cavity of a previously decorated card body. This insetting operation can be effected by depositing a liquid glue in the cavity of the card body before adding the micromodule.
FIG. 2 illustrates another insetting technique. The card body 110 is produced according to a conventional method, for example, by the injection of plastics material into a mould. The cavity 120 is obtained either by milling the card body, or by injection at the time of manufacture of the card body in an adapted mould.
A thermoactivatable adhesive film 23 is deposited by lamination on the dielectric film 15 preferentially before the cutting of the micromodule 100. The latter is inset in the cavity 120 in the card body 110 and glued by reactivating the thermoactivable adhesive 23 by hot pressing by means of a press 24 whose shape is adapted to that of the cavity 120.
The known technologies of manufacturing smart cards have many drawbacks.
In particular, the standard technology uses expensive techniques and a high-quality dielectric. The dielectric used is generally made from an epoxy glass composite or from Kapton.
This is because the dielectric chosen must have properties of good resistance to temperature in order to be compatible with the insetting techniques described previously.
In addition, the geometric definition of the different contact and connection areas is generally obtained by chemical etching of the metallic grid deposited uniformly on the dielectric support. However, chemical etching is an expensive operation.
The French patent No 2 632 100 describes another method for manufacturing a smart card.
Such a method is illustrated in FIG. 3 and uses a conductive frame (lead frame in English) to which the integrated circuit chip is directly fixed. This lead frame is obtained by cropping or punching from a continuous metallic strip, which makes it possible to dispense with the chemical etching operation.
Contact areas 19a and connection areas 19b have been defined in each lead frame of the metallic strip 18.
The method described in this patent consists essentially in laminating a first insulating strip 50 on the external face of the metallic grid 18, which leaves the contact areas 19a free, and laminating two other insulating strips 52 and 54 on the internal face of the grid 18, which surround the connection areas 19b of the chip 10. The chip is then fixed to the internal face of the grid by hard wiring or according to a conventional method of a turned-over chip (xe2x80x9cflip chipxe2x80x9d in English terminology).
This technique makes it necessary to laminate three strips of insulating material on the metallic grid, which requires great precision in indexing.
In addition, the external insulating strip 50 is fixed temporarily, and is in fact intended to be removed after the use of the card.
In addition, the protection of the chip 10 and of its connection wires 17 by coating in a resin is not easy due to the two insulating strips 52 and 54 situated on the internal face of the grid 11 on each side of the chip 10.
Finally, this technique does not afford a complete solution to the problem of the choice of the dielectric since the latter must always have thermal properties compatible with the conventional insetting techniques.
The aim of the present invention is to mitigate the drawbacks of the prior art.
To this end, the present invention proposes a method for manufacturing a smart card making it possible to use inexpensive materials and in particular a low-quality dielectric.
In particular, the present invention proposes to fix a dielectric support film not to the bottom face of the grid but to the top face of the grid, the dielectric film having the shape of a strip with a width such that it can be disposed between the ISO contact areas of the metallic grid.
The object of the present invention is more particularly a method for manufacturing a contact smart card, characterised in that it includes the following steps:
supplying a dielectric support film in strip form;
producing a metallic grid defining contact areas on its top face, and connection areas on its bottom face;
removable fixing of the dielectric support film to the top face of the metallic grid so as to leave the contact areas of the grid free;
gluing the chip and connection to the connection areas of the grid;
cutting the metallic grid in order to obtain a micromodule and attaching the said micromodule in the cavity of a card body.
According to a particular embodiment of the invention, the metallic grid is arched, the dielectric strip being fixed in the arch so as to place the said strip flush with the contact areas of the grid whilst leaving the latter free.
According to one particularity, the dielectric strip has an adhesive face, not peelable at room temperature, intended to be fixed integrally to the metallic grid.
According to one embodiment, the dielectric strip is fixed to the metallic grid by lamination.
According to a variant embodiment, the dielectric strip consists of a polyethylene terephthalate (PET).
According to a variant embodiment, the dielectric strip consists of an acrylonitrile butadiene styrene (ABS)
According to a variant embodiment, the dielectric strip consists of paper.
According to a variant embodiment, the dielectric strip consists of a polyvinyl chloride (PVC).
According to a first embodiment, the chip being connected to the metallic grid by hard wiring, a reactivatable adhesive film is laminated on the metallic grid, the said adhesive being perforated in order to leave the chip and its connection wires free.
According to a second embodiment, the chip being connected to the metallic grid by flipping over, a reactivatable adhesive film is laminated on the metallic grid and covers the rear face of the chip.
According to a preferential embodiment, the micromodule is fitted in the cavity of the card body by activation of the adhesive.
The present invention also relates to an integrated circuit electronic module having a dielectric support film fixed integrally to a metallic grid defining contact areas on its top face, characterised in that the dielectric support film extends partially over the top face of the grid whilst leaving the contact areas free.
According to one characteristic, the dielectric support film is a strip disposed on a middle zone between the zones of the contact areas.
Preferentially, the metallic grid has an arch able to receive, at least partially, the thickness of the dielectric support film.
According to one particular embodiment, the integrated circuit electronic module has an integrated circuit chip attached to a dielectric support strip and connected to a communication interface, characterised in that the communication interface consists of a metallic grid arched so as to encase the thickness of the dielectric strip, the said strip being fixed to the top face of the metallic grid and leaving the contact areas of the grid free..
The present invention applies to any support with an electronic chip, such as a card, comprising an electronic module according to the invention.
The present invention makes it possible to obtain, with a simple and economical method, a thin micromodule, having good resistance to humidity and with a completely flat ISO connection terminal block.
In particular, the method according to the invention makes it possible to use a low-quality dielectric since the latter does not require, the conventional properties of compatibility with the usual insetting techniques.
This is because, and this will emerge more precisely below, the dielectric does not cover the contact areas of the metallic grid. However, during insetting, it is these areas which are pressed or glued with a glue of the cyanoacrylate type.
In addition, the manufacturing method according to the invention has the advantage of allowing the printing of a logo or a serial number or any other distinctive sign on the dielectric strip, alongside the contact areas.
In addition, it is possible, in a method according to the invention, to attach the chip using the adhesive coated on the dielectric strip, and thus avoid an additional gluing step.